Time-resolved terahertz multispectral imaging automatic control system and method based on Labview
Through Labview's producer-consumer architecture and nested event structure, the problems of long data acquisition time and data omission in the time-resolved terahertz spectroscopy imaging system were solved, and automated control and improved data accuracy were achieved.
Patent Information
- Application Number
- CN202510835853.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-20
- Publication Date
- 2025-10-10
AI Technical Summary
Existing time-resolved terahertz spectral imaging systems have problems such as long data acquisition time, missed data in hotspot scanning areas, and complex manual operations, which make it impossible to accurately and timely present spectral imaging images.
A Labview-based producer-consumer architecture is adopted, with a nested event structure and a three-layer For loop design, to achieve coordinated control of components such as the femtosecond laser, delay line, and two-dimensional translation stage. Combined with a multi-exponential fitting algorithm, it automatically identifies and corrects noise or abnormal data, and optimizes scanning parameters to reduce data omissions.
It realizes the automatic control of the system, reduces the data collection time, improves the accuracy and reliability of the data, avoids the omission of data in hot spots, and simplifies user operations.
Smart Images
Figure CN120761330A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the field of spectral imaging, and particularly relates to a Labview-based automatic control system and method for time-resolved terahertz multispectral imaging. BACKGROUND
[0002] Due to unique characteristics, terahertz spectral technology is often used to detect key physical parameters of materials. Time-resolved terahertz spectrum has the characteristics of strong penetration and low photon energy, and can extract important parameters such as carrier lifetime, mobility, doping concentration and conductivity of a sample in a non-destructive state. In addition, terahertz spectrum can be used to detect impurity content, internal foreign matter and moisture content in food and drug detection, so as to ensure the quality and safety of drugs. Terahertz spectral technology has been widely used in research institutions and industrial production departments.
[0003] Such a terahertz system usually uses three femtosecond pulse signals with a certain delay, involves complex timing signal processing, and two-dimensional scanning imaging also complicates the timing signal processing. The existing optical system based on the pump-probe principle generally uses a sequential control method. Under this method, the user cannot control the acquisition process once the scanning starts, resulting in repeated data acquisition and missing of effective data. In order to ensure the effectiveness and accuracy of the data, the scanning step needs to be changed to repeat the scanning of the hot spot area, that is, the area with unevenly distributed active sites or abnormal intensity in the plane. At the same time, such an optical system involves complex optical and mechanical control, resulting in a long time for collecting time-resolved terahertz time-domain spectral images, which may cause damage to some sensitive samples. Such a control method cannot accurately, effectively and timely present the spectral image to the user.
[0004] Therefore, the application provides a Labview-based automatic control system and method for time-resolved terahertz multispectral imaging. SUMMARY
[0005] The application aims to at least solve one of the technical problems existing in the prior art. To this end, the application provides a Labview-based automatic control system and method for time-resolved terahertz multispectral imaging, which is used to solve the technical problems of long invalid acquisition time of time-resolved time-domain spectral images, missing of data in hot scanning areas, and complex manual operation.
[0006] To achieve the above-mentioned purpose, a first aspect of the application provides a Labview-based automatic control system for time-resolved terahertz multispectral imaging, comprising a construction module.
[0007] The construction module is used to establish initialization of serial ports of each component and Labview communication between each component.
[0008] The serial port initialization VI of each component is established, and the connection states of the femtosecond laser, the delay line, the chopper, the phase-locked amplifier, the differential photoelectric detector, the two-dimensional translation table and the NI6810 data acquisition card are checked and initialized.
[0009] The producer cycle is established, and a plurality of event structures are set; the producer cycle is used to generate data and tasks, and the real-time data generated is stored in the buffer;
[0010] The consumer cycle is established, and a plurality of condition structures are set; the consumer cycle is used to take out data from the buffer for processing; the consumer cycle includes consumer cycle 1 and consumer cycle 2.
[0011] The producer-consumer architecture is established based on the producer cycle and the consumer cycle; wherein the producer-consumer architecture includes a main program front panel, a control panel and a plurality of vi of different control modules.
[0012] Preferably, the event structure includes 7 events; wherein event 0 is a synchronization parameter setting, event 1 is used for movable component parameter setting, event 2 is used for initial terahertz multi-dimensional spectral imaging scanning, event 3 is used for displaying the terahertz multi-dimensional spectral image and imaging image of the sample to be measured, event 4 is used for fitting and analyzing the time-resolved terahertz spectral data and imaging data, event 5 is used for feedback control setting and triggering, and event 6 is used for exiting the program; wherein the movable component parameters include delay line 1, delay line 2 and two-dimensional translation table.
[0013] The sample to be measured refers to a graphene / perovskite type material to be detected.
[0014] Preferably, the condition structure in the consumer cycle 1 corresponds to the event 0, the event 1 and the event 2 in the producer cycle;
[0015] The condition structure in the consumer cycle 2 corresponds to the event 3, the event 4 and the event 5 in the producer cycle.
[0016] Preferably, the producer cycle event 2 corresponding to the consumer cycle 1 includes three-layer For loops in the condition structure;
[0017] The first layer For loop sets the movement parameters of the two-dimensional translation table, controls the two-dimensional imaging area size and resolution of the terahertz time-domain spectrum and the optical pumping spectrum; wherein the movement parameters include movement step and movement range.
[0018] The second layer For loop sets the movement parameters of the delay line; wherein the delay line includes delay line 1 and delay line 2, the delay line 1 controls the time resolution and resolution range of the time-resolved terahertz time-domain spectrum, and the delay line 2 controls the time domain range of the terahertz time-domain spectrum.
[0019] The third layer For loop completes the scanning of the moving site, judges whether the chopper high and low level corresponds to the terahertz signal pumped by light; if yes, the time-resolved terahertz time-domain spectrum is calculated, and the spectrum data is automatically stored in the data sub VI; if no, the terahertz time-domain spectrum is calculated, and the spectrum data is automatically stored in the data sub VI.
[0020] It should be noted that when the moving step and the moving range of the delay line are set, a plurality of moving sites will be generated on the entire delay line, and the delay line will stop at the moving site for terahertz spectrum data collection.
[0021] Preferably, the condition structure of the consumer loop 2 corresponds to the event 3, the event 4 and the event 5 in the producer loop;
[0022] The spectrum data in the consumer loop 1 is input into the consumer loop 2, and the spectrum data is associated with the relative moving position of the movable component parameter, to generate a terahertz multi-dimensional spectrum map of the region to be analyzed.
[0023] Preferably, the terahertz multi-dimensional spectrum map includes a terahertz time-domain spectrum, a time-resolved terahertz time-domain spectrum, a three-dimensional time-resolved terahertz time-domain spectrum map, a terahertz time-domain spectrum imaging map, and a time-resolved terahertz time-domain spectrum imaging map.
[0024] It should be noted that the terahertz time-domain spectrum map, the terahertz frequency-domain spectrum map, and the time-resolved terahertz spectrum map are all single-point data collection; here, the imaging map refers to the movement of the two-dimensional translation table, the point-by-point scanning of the region to be measured, and the selection of the time-domain intensity signal data or the frequency-domain intensity signal data under different time delays to form a two-dimensional plane imaging map of the test sample.
[0025] Preferably, the three-dimensional time-resolved terahertz time-domain spectrum map takes the time delay interval of the THZ pulse and the probe light pulse as the X-axis, the time delay interval of the pump light and the probe light pulse as the Y-axis, and the signal intensity value as the Z-axis.
[0026] The terahertz time-domain spectrum imaging map takes the spatial position as the XY-axis, and the signal intensity value as the Z-axis.
[0027] Preferably, the event 4 is used for fitting the time-resolved terahertz spectrum data, including:
[0028] The fitting formula is as follows:
[0029]
[0030] Wherein, τ1 and τ2 are the lifetimes corresponding to different change processes of the molecule, E1 and E2 are the proportions of the corresponding change processes in the total change, and C is the baseline offset.
[0031] Preferably, the event 5 is used for feedback control setting and triggering, including:
[0032] Event 5 removes and feeds back the region with signal noise greater than the preset noise threshold and the difference between the spectral data and the standard threshold greater than the preset difference according to the fitting result of event 4, reestablishes the scanning region and the moving step and repeats the scanning, and records the data.
[0033] The second aspect of the application provides a Labview-based automatic control method for time-resolved terahertz multispectral imaging, including:
[0034] Step S1: initialize the state of each component and detect the communication connection;
[0035] Step S2: set the initial parameters of each component and scan the region to be analyzed;
[0036] Step S3: judge whether the relaxation control is opened; if yes, go to step S4; if no, go to step S5;
[0037] Step S4: collect the spectral data of the terahertz time-domain spectrum under the initial delay time, fit the time-resolved spectral data, and judge whether the fitting parameters are abnormal; if yes, correct the time-resolved range and step parameters; if no, go to step S5;
[0038] Step S5: judge whether the region to be analyzed is abnormal; if yes, correct the parameters of each component, rescan the region to be analyzed, and obtain the two-dimensional scanning imaging graph of the terahertz time-domain spectrum under different time delays; if no, obtain the two-dimensional scanning imaging graph of the terahertz time-domain spectrum under the initial delay time.
[0039] Compared with the prior art, the application has the beneficial effects that:
[0040] The producer of the application circulates through the nested event structure, such as 7 types of events including parameter setting, scanning trigger, feedback control, etc., to allow the user to interrupt or adjust the scanning parameters at any time, such as step size, range, resolution, etc.; specifically, through the three-layer For loop nested design of two-dimensional imaging control, time domain resolution adjustment and site scanning, the system can synchronize and coordinate components such as femtosecond laser, delay line, two-dimensional translation stage, etc., to ensure the strict matching of time sequence signals and spatial scanning, and combined with the multi-exponential fitting algorithm of event 4, the relaxation time τ and the component proportion can be analyzed in real time, and the noise or abnormal data can be automatically identified. For the problem area, the system will trigger event 5 to reduce the step size to 1 / 10 and repeat the collection 3 times to take the average, so as to reduce the data omission of the hot spot area and improve the data reliability; through unified packaging VI and modular design, the system integrates complex device control into the Labview front panel, and the user only needs to set the parameters through the control, without deep hardware operation, the data processing capability can minimize data loss, increase data accuracy, and system control operability. When performing each scan, the data fitting and analysis of the hot spot area are performed, and through automatic correction scanning, the problems of too long invalid collection time of time-resolved terahertz time-domain spectrum image, data omission of hot spot scanning area, and complex manual operation are solved. BRIEF DESCRIPTION OF DRAWINGS
[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, below will briefly introduce the drawings needed to be used in the embodiments or prior art description, obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.
[0042] Figure 1 It is a schematic diagram of the system framework of the present application.
[0043] Figure 2 It is a schematic diagram of the method flow of the present application. DETAILED DESCRIPTION
[0044] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.
[0045] Please refer to Figure 1 The first aspect embodiment of the present application provides a Labview-based time-resolved terahertz multispectral imaging automatic control system, which comprises:
[0046] The Labview sequence structure is established and realized in sequence.
[0047] In the first frame of the sequential structure, a unified package VI is developed for different device interfaces (RS232 / USB / Ethernet) to realize automatic conversion of instruction format. System initialization is realized by connecting the core components such as femtosecond laser, programmable power supply, delay line 1, delay line 2, two-dimensional translation stage, chopper, phase-locked amplifier, differential photoelectric detector, photoconductive antenna and NI6810 data acquisition card, completing the initialization of each component and realizing the bidirectional communication channel.
[0048] Specifically, the connection with the femtosecond laser is established to obtain the working state, laser power, repetition frequency, error state and other information of the femtosecond laser; the connection with the programmable power supply is established to obtain the output voltage of the programmable power supply; the connections with the delay line 1 and the delay line 2 are established to obtain the connection states of the delay lines; the connection with the two-dimensional translation stage is established to obtain the moving step, moving range, trigger mode, zero position, reset position and error state; the connection with the chopper is established to obtain the connection state, trigger mode, sampling rate, duty cycle, sampling rate error code and other information of the chopper; the connection with the phase-locked amplifier is established to obtain the reference frequency, signal source and filter bandwidth information of the phase-locked amplifier; the connection with the differential photoelectric detector is established to obtain the responsivity, common-mode rejection ratio and working state information of the differential photoelectric detector; the connection with the photoconductive antenna is established to obtain the working state and error state information of the photoconductive antenna; and the connection with the data acquisition card is established to obtain the acquisition event, acquisition channel, working trigger mode and error state information of the data acquisition card.
[0049] The While loop structure 1, i.e. the producer loop, is set up in the second frame of the sequential structure, and the parameters of the differential photodetector, the delay line 1, the delay line 2, the two-dimensional translation table and the chopper are set in the producer loop. An event structure is constructed in the While loop structure 1; wherein the event structure includes 7 branches: event 0 is a system synchronization parameter setting, i.e. a value change event of a synchronization trigger button on the main control panel; event 1 is a movable component parameter setting, i.e. a value change event of a button on the main control panel for setting the delay line 1, the delay line 2 and the two-dimensional translation table; event 2 is an initial terahertz multi-dimensional spectral imaging scanning, i.e. a value change event of a button on the main control panel for a relaxation and a two-dimensional scanning; event 3 is for displaying a terahertz multi-dimensional spectral image and an imaging image of a sample to be measured; wherein a value change event of a button on the main control panel for an X-axis position, a Y-axis position, a delay time 1 and a delay time 2, i.e. a value change event of a button on the main control panel for displaying a three-dimensional time-resolved terahertz time-domain spectral image, a two-dimensional terahertz time-domain spectral imaging image, a two-dimensional terahertz spectral imaging image under different time delays, and a terahertz time-domain spectral image of different sites; event 4 is a time-resolved spectral data or imaging data fitting and analysis, i.e. a value change event of a button on the main control panel for data selection, formula selection and correction; event 5 is a feedback control setting and triggering, i.e. a value change event of a parameter correction pause button and a correction button on the main control panel; and event 6 is a program exit, i.e. a value change event of a termination button on the main control panel.
[0050] The While loop structure 2, i.e. the consumer loop 1, is set up in the second frame of the sequential structure, and a condition structure is established in the consumer loop 1, which corresponds to three events in the producer loop: event 0, event 1 and event 2; wherein please refer to Figure 2 , event 2 includes three layers of For loops, and the user can control the two-dimensional imaging area size and resolution of the terahertz time-domain spectrum and the time-resolved terahertz spectrum through the first layer of For in event 1; after the first layer of For, it is necessary to judge whether the relaxation control is opened through event 1; if yes, the second layer of For is entered to control, and the time delay range of the terahertz time-domain spectrum and the time-resolved terahertz time-domain spectrum is determined according to the moving step and the moving range of the delay line 1 and the delay line 2; if no, the terahertz time-domain spectrum range is determined according to the moving step and the moving range of the delay line 1; the third layer of For scans each moving site, and the spectral data is automatically stored in the data sub-VI; wherein the spectral data includes the time-resolved terahertz spectral data and the terahertz time-domain spectral data.
[0051] A while loop structure 3, i.e. a consumer loop 2, is set up in the second frame of the sequential structure, and a conditional structure is established in the consumer loop 2, which corresponds to three events in the producer loop, i.e. event 3, event 4 and event 5. Event 3 reads the data sub-VI in real time according to the set data reading parameters, and constructs a terahertz spectrum; event 4 displays the fitting result on the main panel; event 5 compares the result in event 4 with the preset parameters, and automatically generates correction parameters of each moving part parameter, and the user can decide to trigger the data feedback adjustment process according to the result.
[0052] In the third frame of the sequential structure, the two-dimensional translation stage is reset to zero, the delay line is reset to zero, the femtosecond laser is turned off, the data acquisition card cache is released, a timestamp, operation record and error statistics log file are generated, and finally the memory queue is emptied.
[0053] In event 5, there are a separate pause button and a correction button, and when both buttons are triggered, the system starts the feedback correction process.
[0054] After executing the data feedback correction process, the system automatically analyzes the collected data. In the acquisition process, real-time two-dimensional imaging of the terahertz time-domain spectrum is performed, and then two-dimensional scanning imaging detection is performed. When an abnormal signal point is found in the image, a correction parameter is generated, and detection is performed again. Finally, the terahertz time-domain spectrum, the time-resolved terahertz spectrum, the three-dimensional time-resolved terahertz time-domain spectrum, the two-dimensional terahertz time-domain spectrum imaging graph and the three-dimensional time-resolved terahertz spectrum imaging graph of the sample are obtained through data selection and integration.
[0055] It should be noted that the time-resolved terahertz spectrum data needs to be first subjected to multi-exponential fitting and component analysis to analyze the relaxation time and lifetime components and generate correction parameters, and then re-detect and continue two-dimensional scanning imaging detection.
[0056] Referring to Figure 2 The second aspect of the present application provides an automatic method for time-resolved terahertz multispectral imaging based on Labview, which comprises:
[0057] Step S1: initialize the state of each component and detect the communication connection;
[0058] Step S2: set the initial parameters of each component and scan the area to be analyzed;
[0059] Step S3: determine whether the relaxation control is turned on; if yes, go to step S4; if no, go to step S5;
[0060] Step S4: collecting the spectral data of the terahertz time-domain spectrum under the initial delay time, fitting the time-resolved spectral data, judging whether the fitting parameters are abnormal or not; if yes, modifying the time-resolved range and step length parameters; if no, entering step S5;
[0061] Step S5: judging whether the region to be analyzed is abnormal or not; if yes, modifying the parameters of each component, rescanning the region to be analyzed, and obtaining the two-dimensional scanning imaging graph of the terahertz time-domain spectrum under different time delays; if no, obtaining the two-dimensional scanning imaging graph of the terahertz time-domain spectrum under the initial delay time.
[0062] The above examples are only used to illustrate the technical method of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical method of the present application.
Claims
1. A time-resolved terahertz multispectral imaging automatic control system based on Labview, characterized in that: Includes building blocks; Construction module: used to establish serial port initialization of each component and Labview communication between components; Establish a producer loop and set up several event structures; the producer loop is used to generate data and tasks, and store the generated real-time data in the buffer; Create a consumer loop and set several conditional structures; the consumer loop is used to retrieve data from the buffer for processing; the consumer loop includes consumer loop 1 and consumer loop 2; Establish a producer-consumer architecture based on the producer loop and the consumer loop.
2. The Labview-based time-resolved terahertz multispectral imaging automatic control system according to claim 1, characterized in that: The event structure includes 7 events; among them, event 0 is used for synchronization parameter setting, event 1 is used for movable component parameter setting, event 2 is used for initial terahertz multi-dimensional spectral imaging scanning, event 3 is used to display the terahertz multi-dimensional spectrum diagram and imaging diagram of the sample to be tested, event 4 is used to fit the time-resolved terahertz spectrum data, event 5 is used for feedback control setting and triggering, and event 6 is used to exit the program; among them, the movable component parameters include delay line 1, delay line 2 and two-dimensional translation stage.
3. The Labview-based time-resolved terahertz multispectral imaging automatic control system according to claim 2, characterized in that: The conditional structure in the consumer loop 1 corresponds to event 0, event 1, and event 2 in the producer loop; The conditional structure in the consumer loop 2 corresponds to events 3, 4, and 5 in the producer loop.
4. The Labview-based time-resolved terahertz multispectral imaging automatic control system according to claim 3, characterized in that: The producer loop event 2 corresponding to the consumer loop 1 includes three layers of For loops in the conditional structure; The first layer of the For loop sets the movement parameters of the two-dimensional translation stage to control the size and resolution of the two-dimensional imaging area of terahertz time-domain spectroscopy and optical pump spectroscopy. The movement parameters include the movement step size and movement range. The second layer of the For loop sets the movement parameters of the delay line. The delay line includes delay line 1 and delay line 2. Delay line 1 controls the time resolution and resolution range of the time-resolved terahertz time-domain spectroscopy, while delay line 2 controls the time domain range of the terahertz time-domain spectroscopy. The third-level For loop completes the scanning of the moving position and determines whether the high and low levels of the chopper correspond to the terahertz signal with optical pumping. If so, the time-resolved terahertz time-domain spectrum is calculated and the spectral data is automatically stored in the data subVI. If not, the terahertz time-domain spectrum is calculated and the spectral data is automatically stored in the data subVI.
5. The Labview-based time-resolved terahertz multispectral imaging automatic control system according to claim 3, characterized in that: The conditional structure of the consumer loop 2 corresponds to events 3, 4, and 5 in the producer loop; The spectral data in consumer loop 1 is input into consumer loop 2, and the spectral data is associated with the relative movement positions of the two-dimensional translation stage, delay line 1 and delay line 2 to generate a terahertz multi-dimensional spectrum of the area to be analyzed.
6. The Labview-based time-resolved terahertz multispectral imaging automatic control system according to claim 2, characterized in that: The terahertz multi-dimensional spectrum diagram includes a terahertz time-domain spectrum, a time-resolved terahertz time-domain spectrum, a three-dimensional time-resolved terahertz time-domain spectrum diagram, a terahertz time-domain spectrum imaging diagram, and a time-resolved terahertz time-domain spectrum imaging diagram.
7. The Labview-based time-resolved terahertz multi-spectral imaging automatic control system according to claim 6, characterized in that: The three-dimensional time-resolved terahertz time-domain spectrum has the time delay interval between the THZ pulse and the detection light pulse as the X-axis, the time delay interval between the pump light and the detection light pulse as the Y-axis, and the signal intensity value as the Z-axis; The terahertz time-domain spectrum imaging diagram uses spatial position as the XY axis and signal intensity value as the Z axis.
8. The Labview-based time-resolved terahertz multi-spectral imaging automatic control system according to claim 2, characterized in that: The event 4 is used to fit the time-resolved terahertz spectroscopy data, including: The fitting formula is as follows: Among them, τ1 and τ2 are the lifetimes of different molecular change processes, E1 and E2 are the proportions of their corresponding change processes in the total change, and C is the baseline offset.
9. The Labview-based time-resolved terahertz multi-spectral imaging automatic control system according to claim 2, characterized in that: Event 5 is used for feedback control setting and triggering, including: Event 5, based on the fitting results of event 4, removes and feeds back the areas where the signal noise is greater than the preset noise threshold and the difference between the spectral data and the standard threshold is greater than the preset difference value, re-establishes the scanning area and the moving step size, repeats the scanning, and records the data.
10. A Labview-based automatic control method for time-resolved terahertz multi-spectral imaging, which is based on the Labview-based automatic control system for time-resolved terahertz multi-spectral imaging according to any one of claims 1 to 9, and is characterized in that: include: Step S1: Initialize the status of each component and detect the communication connection; Step S2: setting the initial parameters of each component and scanning the area to be analyzed; Step S3: Determine whether the relaxation control is on; if yes, proceed to step S4; if not, proceed to step S5; Step S4: collecting spectral data of the terahertz time-domain spectrum at the initial delay time, fitting the time-resolved spectral data, and determining whether the fitting parameters are abnormal; if so, correcting the time resolution range and step size parameters; If not, proceed to step S5; Step S5: Determine whether the area to be analyzed is abnormal; if so, correct the parameters of each component, rescan the area to be analyzed, and obtain a two-dimensional scanning image of the terahertz time domain spectrum under different time delays; if not, obtain a two-dimensional scanning image of the terahertz time domain spectrum under the initial delay time.